Hell's Kitchen winner Ja'Nel Witt has been denied her grand prize of a head chef job at a Las Vegas restaurant after reportedly failing a drug test.Witt in late July was crowned the winner of season 11 of Hell's Kitchen by celebrity chef and show host Gordon Ramsay.She won the grand prize of a $250,000-a-year head chef position at the Gordon Ramsay Pub & Grill at the Caesars Palace casino in Las Vegas, but tweeted on Friday that she would not be taking the job.But according to TMZ, she'll receive a $250,000 cash prize instead of the role.